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Perpendicular magnetic recording medium with multilayer recording structure including intergranular exchange enhancement layer

a multi-layer recording and magnetic recording technology, applied in the field of perpendicular magnetic recording media, can solve the problems of high media noise, random shift of readback signal peaks, and increase intrinsic media noise, and achieve the effects of good recording properties, less susceptible to corrosion, and poor corrosion resistan

Inactive Publication Date: 2008-06-12
INT PAPER CO +1
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Benefits of technology

[0013]The invention is a perpendicular magnetic recording medium with a multilayer RL structure that includes a ferromagnetic intergranular exchange enhancement layer for mediating intergranular exchange coupling in the other ferromagnetic layers in the RL structure. In a first embodiment the RL structure is a multilayer of two lower ferromagnetic layers (MAG1 and MAG2), each with reduced or no intergranular exchange coupling, and a ferromagnetic capping layer as the intergranular exchange enhancement layer on top of and in contact with the upper ferromagnetic layer MAG2. MAG1 may be a granular polycrystalline Co alloy and an oxide or oxides of Ta, MAG2 may be a granular polycrystalline Co alloy and an oxide of Si, and the capping layer may be an oxide-free CoCr alloy. The lower Ta-oxide-containing MAG1, which has good recording properties but poor corrosion resistance, is located farther from the disk surface so as to be less susceptible to corrosion, and the Si-oxide-containing MAG2, which has poor recording properties but good corrosion resistance, is in contact with the capping layer.

Problems solved by technology

Both horizontal and perpendicular magnetic recording media that use recording layers of granular polycrystalline ferromagnetic Co alloys exhibit increasing intrinsic media noise with increasing linear recording density.
Media noise arises from irregularities in the recorded magnetic transitions and results in random shifts of the readback signal peaks.
High media noise leads to a high bit error rate (BER).
Perpendicular magnetic recording media with RLs containing oxides or other segregants for improved SNR are subject to thermal decay.
As the magnetic grains become smaller to achieve ultrahigh recording density they become more susceptible to magnetic decay, i.e., magnetized regions spontaneously lose their magnetization, resulting in loss of data.
There are several problems with RL structures that have a single lower ferromagnetic layer with reduced or no intergranular exchange coupling, such as oxide-containing granular Co alloy layers, covered by an upper continuous oxide-free capping layer for enhancing intergranular exchange coupling.
When the lower ferromagnetic layer is a Ta-oxide-containing layer the RL structure has unacceptable corrosion resistance.
When the lower ferromagnetic layer is a Si-oxide-containing layer the RL structure has less than optimal recording performance.
This large thickness for the RL structure can adversely affect resolution and writability because it produces an increase in the transition width (or ‘a’ parameter) causing adjacent transitions to increasingly interfere when readback at high recording density.

Method used

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  • Perpendicular magnetic recording medium with multilayer recording structure including intergranular exchange enhancement layer
  • Perpendicular magnetic recording medium with multilayer recording structure including intergranular exchange enhancement layer
  • Perpendicular magnetic recording medium with multilayer recording structure including intergranular exchange enhancement layer

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first embodiment

[0028]the perpendicular magnetic recording disk of this invention is illustrated in FIG. 5, which is schematic of a cross-section of the disk. The RL structure is a multilayer of two lower ferromagnetic layers (MAG1 and MAG2), each with reduced or no intergranular exchange coupling, and a CP on top of and in contact with the upper ferromagnetic layer MAG2.

[0029]MAG1 is formed of a granular polycrystalline Co alloy, such as a CoPt or CoPtCr alloy, and an oxide or oxides of Ta. MAG2 is formed of a granular polycrystalline Co alloy, such as a CoPt or CoPtCr alloy, and an oxide or oxides of Si. The CP may be formed of Co, or ferromagnetic Co alloys, such as CoCr alloys. The Co alloys of the CP may include one or both of Pt and B. The CP is deposited directly on MAG2, with MAG2 being deposited directly on MAG1. MAG1 and MAG2 are sputter deposited at relatively high pressure (e.g., 10-20 mTorr) in the presence of oxygen. Alternatively MAG1 and MAG2 may be sputter deposited from an oxide-c...

second embodiment

[0032]In the perpendicular magnetic recording medium of this invention, as depicted in FIG. 6, the RL structure is a multilayer with an intergranular exchange enhancement interlayer (IL) in between two ferromagnetic layers, MAG1 and MAG2. The total thickness of MAG1+MAG2 is the same as the thickness of MAG in the prior art of FIG. 3. The IL functions like the CP. However, the intergranular exchange from the IL acts on two interfaces instead of one. Also, because the IL is acting on half the thickness of magnetic layer than in the prior art of FIG. 3, it can be made thinner. Therefore, the same or better effects as achieved with the prior art can be achieved with less total thickness for the RL structure.

[0033]In the embodiment of FIG. 6, the MAG1 and MAG2 layers are preferably formed of a granular polycrystalline Co alloy, such as a CoPt or CoPtCr alloy, with a suitable segregant such as an oxide or oxides of one or more of Si, Ta, Ti, Nb, Cr, V and B. Also, like in the embodiment o...

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Abstract

A perpendicular magnetic recording medium has a multilayer recording layer (RL) structure that includes a ferromagnetic intergranular exchange enhancement layer for mediating intergranular exchange coupling in the other ferromagnetic layers in the RL structure. The RL structure may be a multilayer of a first ferromagnetic layer (MAG1) of granular polycrystalline Co alloy with Ta-oxide, a second ferromagnetic layer (MAG2) of granular polycrystalline Co alloy with Si-oxide, and an oxide-free CoCr capping layer on top of and in contact with MAG2 for mediating intergranular exchange coupling in MAG1 and MAG2. The RL structure may also be a multilayer of an intergranular exchange enhancement interlayer (IL) in between two ferromagnetic layers, MAG1 and MAG2, each with reduced or no intergranular exchange coupling. Because the IL is in direct contact with both MAG1 and MAG2, it directly mediates intergranular exchange coupling in each of MAG1 and MAG2.

Description

BACKGROUND OF THE INVENTION[0001]1. Field of the Invention[0002]This invention relates generally to perpendicular magnetic recording media, such as perpendicular magnetic recording disks for use in magnetic recording hard disk drives, and more particularly to a perpendicular magnetic recording medium with a multilayer recording layer having optimal intergranular exchange coupling.[0003]2. Description of the Related Art[0004]Horizontal or longitudinal magnetic recording media, wherein the written or recorded bits are oriented generally parallel to the surfaces of the disk substrate and the planar recording layer, has been the conventional media used in magnetic recording hard disk drives. Perpendicular magnetic recording media, wherein the recorded bits are stored in the recording layer in a generally perpendicular or out-of-plane orientation (i.e., other than parallel to the surfaces of the disk substrate and the recording layer), provides a promising path toward ultra-high recordin...

Claims

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Application Information

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Patent Type & Authority Applications(United States)
IPC IPC(8): G11B5/706
CPCG11B5/66G11B5/65G11B5/672G11B5/1278G11B2005/0029Y10S428/90
Inventor BERGER, ANDREAS KLAUSDAI, QINGDO, HOA VANIKEDA, YOSHIHIROMARGULIES, DAVID THOMASSUPPER, NATACHA F.TAKANO, KENTAROXIAO, MIN
Owner INT PAPER CO
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